The present invention concerns a system for storing and restoring video-films, based on optical disks of very high definition.
At present, all television and cinema archives use magnetic supports, like tapes and cassettes, of different formats. Those supports are characterized in the worsening of the signal quality due to time and ambient; furthermore, the storing supports request spaces that are often precious.
The use of the known storing systems for video-films shows the following disadvantages:
the manual managing of the storing supports: the use of magnetic cassettes as a support for the storing of films makes the managing of great archives rather difficult. In_fact, it is difficult or rather expensive to use robotic systems in the real registration phase (i.e. the assignation of a material place to the cassette to be kept) as well as in the search phase (i.e. the finding of the material space previously assigned);
the need of duplication of the contents in case of contemporary use by a plurality of users: the film that has been recorded onto a cassette may not be used at the same time and independently by more than one person. Therefore, it is necessary to make a copy of the cassette each time the,use of the same is requested by a plurality of persons at the same time;
the magnetic tape is a recording support that undergoes wear due to use an ageing, and this means that the recorded signal undergoes an unavoidable decay with time passing by, the reading and the copies made. This problem has been partially attenuated by the introduction of digital recording techniques, but is far from being solved;
there is no possibility of checking the content before use: the check of the real content of the cassette and therefore its conformity to the content requested may be performed only by a videorecorder. Therefore, the cassette must be sought for in the archive, put into a videorecorder and checked about its content. In very vast archives with approximate indexing, the search for the requested cassette may become a long lasting affair;
the signal may not be distributed on geographic data nets: the recording format onto the tapes used until now does not allow an easy distribution of the signal onto geographic data nets, because a very high band is requested or also it is necessary to perform a compression before transmission. This problem also returns to the need that the archive of the video-films be near to the place where the recorded films will be used;
the space taken and the many formats of the recording supports: the dimension of the magnetic cassettes requests great rooms for storing. Furthermore, the progress in the recording supports has caused in general a non-homogeneous composition of the video archives, with cassettes of different shape and therefore the need of readers for all formats;
the cost of the recording supports: the decay due to time and to wear of the magnetic tapes forces to use materials of very high quality in the realization of professional video-cassettes, and this implies a very high cost of the cassettes.
It is the aim of the system according to the present invention to supply a means for recording films and for using the recorded material that is as much as possible automated, thus simplifying the searching, loading, use and recording operations of video-films.
The suggested system makes use of DVD disks (Digital Versatile Disk) as a support for the recording of films; these disks are the latest standard for recording digital informations onto an optical support, with the dimensions of a conventional audio CD (diameter: 12 cm), so that said films may be recorded onto said disks in a compressed format according to the MPEG-2 standard, which is the standard universally accepted for codification and compression of the digital video, and where the algorithm allows to modify the compression factor according to the requested quality, from a few Mbps to a considerable number of Mbps. The different recording technology used allows to solve the problems shown by the known recording systems.